Bandsaw catcher device

ABSTRACT

Roller means mounted on a bandsaw catcher and operable to lift a bandsaw positioned thereon above the periphery of the adjacent upper mill wheel to facilitate the transfer of the bandsaw to the mill wheel.

PATENTE SEP 'I |971 /N VEN TOR HOWARD V. DOUGLS k Q a). um, 'C' "'ggl" 'ORNMYS BANDSAW CATCIIER DEVICE BACKGROU ND OF THE INVENTION l. Field of the Invention This invention relates to sawing of wood using a bandsaw, and pertains to an improvement in conventional band saw catchers or guards therefor.

2. Description of the Prior Art While bandsaw guards are old and well known in the art, and attachments therefor have been developed, it appears that no one prior to the applicant has been concerned with the problem of providing means for facilitating the transfer of a bandsaw from its catcher or guard to the adjacent upper mill wheel.

Bandsaws, as used in conventional mills, are approximately 55 feet long and weigh approximately 800 pounds. To install a new r repaired bandsaw or to return one which has left the mill wheels and which is at rest on the catcher or guard requires the services of four men. Two meri are required at the upper mill wheel, the men being equipped with hooks to engage the upper looped end of the saw' to pull upwardly and laterally thereon to shift the saw blade from the catcher to the mill wheel, while two men press inwardly and upwardly at the opposed sides of the saw to assist in the transfer effort. This is a difficult and dangerous operation.

Over a period of years, band saw catchers or guards have been required by law, but in this interim few basic changes have evolved. Substantially all such guards or catchers have an arcuate configuration including a platform extending through, perhaps, an arc of usually less than 180. The upper surface of the platform is positioned in a laterally spaced position relative to the adjacent upper mill wheel and below the upper surface of the wheel, whereby when a bandsaw slides off its upper mill wheel it is caught on the platform. Some catchers or guards are provided with fixed raised guard flanges extending above the upper surface of the platform, as in the U.S. Pat. to Wallace H. Dodge, No. 294,452, or similar guards which are adjustable to operative and inoperative positions as is shown in the U.S. Pat. to August Isaacson, No. 1,128,879. None of the patents, however, relate to the invention at hand, but they do serve to illustrate the general state of the art.

Perhaps the United States patent to Gustavus H. Zschech is more directly in point for this patentee mounts a plurality of roller devices on a catcher, the rollers being positioned in such a manner as to receive a thrown band saw thereon and to frictionally bring its movement to a halt. The rollers are fixed to the guard and in no way function to facilitate the'shfting of the saw blade from the catcher for installment on the mill wheels.

SUMMARY OF THE INVENTION This invention pertains to an improvement in a band saw catcher which may be of conventional construction. The improvement, per se, relates to means on a catcher operable to elevate the upper end of a band saw blade and to somewhat expand the arcuate configuration thereof so that the bandsaw blade is disengaged from the catcher platform and is raised above the adjacent upper mill wheel whereby it may be easily shifted laterally from the platform onto the wheel, the opera tion being performed with but a single mechanic. To this end, the catcher is provided with a plurality of carriages mounting roller wheels spaced arcuately relative to the catcher platform with the rollers normally being positioned below the upper surface thereof.

Manually operable linkage means mounted on the catcher the roller wheels to raise beyond the outer surface of the platform to engage portions of the band saw upper loop supported thereon, whereby the band saw is elevated and the loop extended to permit the lateral shifting thereof from the platform to the adjacent upper mill wheel. Thereafter, the roller wheels are returned to their normal positions.

It is a further object of this invention to provide means of the type described immediately above, such means being noncomplex in construction and assembly, inexpensive to manufacture and maintain, and which is rugged and durable in use.

Other and further objects and advantages of the instant invention will become more apparent from a consideration of the following specification when read in the light of the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front elevational view of a conventional saw blade catcher for a bandsaw assembly, the catcher being illustrated as modified in accordance with this invention;

FIG. 2 is a side elevational view of the catcher shown in FIG. ll, the catcher being illustrated iin a first operative position relative to the top mill wheel of a conventional bandsaw assembly;

FIG. 3 is an enlarged vertical transverse cross-sectional view showing the catcher in its first operative p'osition in full lines, and its second operative position in dotted lines, FIG. 3 being taken substantially on the vertical plane ofline 3-3 of FIG. I, looking in the direction of the arrows;

FIG. 4 is an enlarged fragmentary detail cross-sectional view, FIG. 4 being taken substantially on the horizontal plane oflne 4-14 of FIG. 3, looking in the direction of the arrows; and

FIG. 5 is an enlarged fragmentary detail cross-sectional view, FIG. S being taken substantially on the vertical plane of line 5-5 of FIG. 3, looking in the direction of the arrows.

DESCRIPTION OF THE PREFERRED EMBODIMENT Reference numeral 10 designates, in general, a conventional bandsaw catcher as modified in accordance with the teachings of this invention. THe catcher l0 includes the usual back frame 12 comprising a pair of identically constructed forwardly facing vertically elongated laterally spaced and parallel substantially U-shaped side frame channel members 14, 16. Each channel member is provided with an elongated substantially rectangular bight 18 from the longitudinally extending marginal edges of which laterally project spaced and substantially parallel side flanges 20, 22.

The frame members 14, 16 are rigidly connected together, intermediate their respective upper and lower ends, by means of a third transversely extending U-shaped channel frame member 24 having an elongated substantially rectangular bight 26 from the longitudinally extending marginal edges of which laterally project a pair of elongated laterally spaced and substantially parallel flanges 28, 30. To effect this connection, the flanges 28, 30 are formed with cutouts (not shown) to receive the flanges 20, 22 therein, and the channel members 14, 16, 24 are subsequently welded together. Since this is conventional crossbracing, this detail has not been shown in the drawings. To serve a function to be described below, it will be observed that the opposed ends of the frame member 24 prothe lower ends of the channel members 16, 18 and the outer f free edges of its flanges are rigidly connected by conventional means (not shown) to the outer free edges of the flanges 20, 22 of the frame members 14, 16. Fixedly connected to the remotely disposed sides of each pair of flanges 20, 22 adjacent their respective upper ends are, respectively, a pair of forwardly projecting gusset plates 40, 42.

The gusset plates terminate in integrally formed substan tially rectangular upper end portions 40A, 42A. At 44 is generally indicated a downwardly opening hoist channel member having an inverted V-shaped configuration in front elevation (see FIG. I), this channel member including a top plate 46 from the longitudinally extending sides of which depend a pair of oppositely disposed front and rear walls 48, 50, respectively. The opposed ends of the channel member 44 are fixedly connected, by conventional means and in the usual manner, on the upper end portions 40A, 42A, and since this construction is old and well known in the art and in view of the fact that it fonns no part of the present invention, no further description thereof is deemed necessary. In passing, however, it should be noted that an upright lug 52 is fixedly connected to the apex of the plate 46, the lug 52 being apertured as at 54 to releasably receive a hoisting hook 56 of a conventional hoist (not shown).

The back frame 12 is completed by connecting a plurality of stub shafts 58 (see FIG. 4) on each bight 18 to project rearwardly therefrom and on each of which is secured a shoe 60.

The catcher 10, as herein described and illustrated, includes a front frame generally indicated by reference numeral 62. Basically, the front frame 62, as well as the back frame 12, is a conventional construction, but it is to this assembly that the present invention is addressed.

lnsofar as the prior art teaches, the frame assembly includes a pair of identically constructed arcuately shaped front and back angle irons or members 64, 66 disposed in laterally spaced, parallel and confronting relationship relative to one another. Each angle member comprises an arcuate top wall 68 and an integrally connected depending sidewall 70. The sidewall 70 of the angle member 66 is conventionally connected to the channel members 14, 16 and, as is seen in FIG. 1, its remotely disposed ends project beyond the remotely disposed sides thereof. In the usual manner, the remotely disposed ends of the angle member 66 are fixedly connected to the adjacent ends of the channel member 26.

In the usual manner, the two angle members 64, 66 are connected together by a plurality of elongated substantially rectangular bandsaw catcher bars 71 disposed in arcuately spaced relationship relative to the top walls 68 on which their remotely disposed ends are fixedly connected. To provide rigidity and stability to the front frame, a plurality of brace rods 72 have one of their respective ends fixedly connected on the bight 34 and diverge upwardly and away from one another for rigid connection with the top wall 68 of the front angle member 64. ln the construction shown, one end of the rods 72 is o'set at 73 and terminates in an enlarged cylindrical head 74. To make this assembly, the other ends of the rods 72 are first passed through suitable openings 76 (see FIG. 1) formed in the bight 34 to bring the heads 74 into engagement with the inner side of the bight 34 after which the heads are rigidly connected thereto.

This completes a brief description of the bandsaw catcher constructed in accordance with modern prior art teachings. There are, of course, band saw catchers presently in use which are not built exactly as described above, but the basic components are the same, and most of these may be easily modified in accordance with the teachings of this invention without major costs and without radial structural changes. The present invention may also be incorporated in newly manufactured catchers as well as being added as an accessory to those presently constructed.

As has been mentioned above, it is one of the major objects of this invention to provide means on a band saw catcher to facilitate the return of the bandsaw from the catcher to the upper mill wheel. Such means are described below.

Thus, and to this end, a plurality of angle irons 78, 80 (see FIGS. 3 and 5), arranged in pairs, extend between and have their respective opposed ends fixedly connected to the angle irons 64, 66 below the top walls 68. The pairs of angle irons 78, 80 are disposed in arcuately spaced relationship relative to one another and are located between preselected adjacent pairsy of blocks 71, and with at least one pair thereof being disposed at or adjacent to the spices of the angle irons 64, 66. Each pair of angle irons 78, 80 has confronting laterally spaced and parallel flanges 82, 84, respectively.

At 86 is generally indicated a carriage which comprises a pair of laterally spaced substantially rectangular parallel and confronting carriage plates 88, 90 fixedly connected together on transversely extending first stub shafts 92 and second stub shafts 94, 95 which have their opposed ends projecting beyond the remotely disposed sides of the plates 88,90. All of the shafts have their respective axes disposed horizontally and parallel with respect to one another. Each of the shafts 92, 94 supports a roller wheel 96 thereon intermediate the sideplates 88, 90, the wheels being tangentially arranged in spaced relationship relative to one another. One such carriage is provided for each pair of angle irons 78, 80.

Referring now more specifically to FIGS 3 and 5, it will be seen that the adjacent pair of ends of a pair of levers 98, 100 are pivotally connected on the remotely disposed between and beyond the flanges 82, 84 in surface-to-surface engagement with the confronting sides thereof. The levers 98, 100, centrally of the ends thereof, are pivotally connected on the flanges 82, 84, respectively, on pivot pins 102, 104. ln a similar manner, the adjacent ends of pair of elongated links 106, 108 are pivotally connected on the extended ends of the pins 95, and their respective other ends extend downwardly between the flanges 82, 84 and are pivotally connected on pivot pins 110 carried on these flanges.

It is seen that the bandsaw catcher frame is further modified by providing a subframe 112, 114 at each remotely disposed end thereof, the subframe being of identical construction. Each subframe comprises a pair of elongated substantially flat rectangular straps 116, 118 which terminate at one of their respective ends in lugs 120, 122 supported on pivot pins 124, 126 carried on pairs of bosses 128 and 130, the latter being secured on, to depend from, the remotely disposed ends of the angle irons 64, 66.

Fixedly connected on the outer sides of the straps 116, 118 is another carriage 86 identically constructed with respect to the carriage 86 with the exception of the omission of the links and the levers of the first described carriages, and the fact that the diverging flanges are fixedly secured on the outer sides of the aforementioned straps. All other common components carry the same reference numerals, but to which has been added a prime mark.

Reference numeral 1 36 denotes an elongated substantially -rectangular backplate fixedly connected on the channel member 32 between its flanges 36, 38. Fixedly connected lon the backplate centrally of its ends is a first rearwardly projecting hollow cylindrical journal 138 and laterally displaced therefrom is a second similar journal 140. Fixedly connected on the side wall 70, substantially at the apex of the angle iron 66, is a third substantially hollow cylindrical journal 142 coaxially aligned with the journal 138, and a fourth journal 144 is also fixed on the sidewall 70 coaxially aligned with the journal and being laterally spaced from the journal 142.

Reference numeral 146 indicates a first operating shaft having its opposed ends joumaled for rotation in the alignedjournals 138, 142, and this shaft is provided with stop flanges 146, 148 at the axial vertical shifting thereof. lt should be observed that to effect the journaling the shaft 146 passes through suitable aligned openings 150, 152, formed in the flanges 28, 30. The upper end of the shaft 146 terminates in wrench head 154, and this shaft adjacent its lower end is externally threaded at 156.

A second operating shaft 158 is provided and has its opposed ends joumaled for rotation in the aligned journals 140, 144. This shaft, like the shaft 146, is provided with stop flanges (not shown) and passes through a second set of aligned openings (not shown) formed in the flanges 28, 30, all as desired immediately above the connection with the shaft 146. The shaft 158, as the shaft 146, is provided with a wrench head 160 at its upper end and is externally threaded at 162 adjacent thereto.

Threaded on the shaft 146 is an elongated internally threaded collar 164 from which projects the three ears 166, 168, 170. One end of an elongated compound rod 172 is pivotally connected on a pivot pin 174 to the ear 166, and its other or upper end is pivotally connected between the lower ends of the levers 98, 100 located adjacent the apices of the angle irons 64, 66 on a pivot pin 176. Other similar rods 178,

180 connect at their respective lower ends to the ears 168, 170 by pivot pins 182, 184, respectively, and their respective other upper ends are similarly connected at 186, 188 to the pairs of levers 98, 100 at the opposite sides of the centermost ones thereof referred to above, reference being made to FIG. 1. The rods 172, 178, 180 are recited as being compound in that each has turnbuckle means 190 interposed to adjust their effective lengths.

In a similar manner, an internally threaded collar 192 is threaded on the shaft 162, the collar 192 having a diverging pair of ears 194, 196 integral therewith. Pivot pins 198 pivotally connect the upper ends of a pair of compound rods 200, 202 on the ears 194, 196, respectively, and the other or lower ends of the rods 202 are pivotally connected on pins 204 carried on lugs 206, 208 secured on the inner sides of the straps 116. Rods 200, 202 are also made compound through the interposition of the tumbuckle means 210 therein to adjust their effective lengths.

FIGS. 1, 2 and 3 are illustrate the carriages 86, 86' in their first operative positions. To achieve these positions, a socket wrench (not shown) was first engaged with the head 154 to turn the shaft 146 in an appropriate direction, this turning causing the collar 192 to shiftaxially on its associated shaft. The turnbuckles 190 were also adjusted in such a manner that the apices of the lower wheels 96 are spaced slightly below the upper planar surfaces of the adjacent blocks 71. A similar socket wrench was also engaged with the head 160 to turn the shaft 158 in a selected direction, and the tumbuckles 210 were also adjusted so that the frames 112, 1 14 are positioned, preferably, inside of the arcuate plane of the top wall 68.

The adjustments must also ensure that when the shaft 146 is turned in the opposite direction, the carriages 86 will move outwardly and upwardly beyond the planes of the outer surfaces of the blocks 71 to reach their respective second operative positions shown in dotted lines in FIG. 3. In a similar manner, the shaft 158 is rotated and the turnbuckles 210 are adjusted so that the frames 112, 114 move outwardly and upwardly to their dotted line positions shown in FIG. 1, this being their second operative position. In this second operative position of the carriages 86', the apices of the roller wheels 96 extend beyond the arcuate plane of the sidewalls 68 to serve a function to be described.

Reference numeral 212 denotes a conventional saw mill pit having a floor 214 extending transversely thereover and the pit includes a back wall 216 against which a pair of vertical, laterally spaced and substantially parallel C-shaped tracks 216, 218 of identical construction is superimposed and secured. Each of' the tracks includes a bight 220 and a pair of forwardly spaced confronting flanges 222, 224, and the latter are laterally spaced from one another to define vertically extending slots 226 therebetween. The lower ends of each track are closed by an abutment member 228. The tracks 218, 220 slidably receive the shoes 60 therein and the abutment members are engaged thereby to limit the downward movement of the band catcher relative thereto. The pit 212 is normally provided with an opening 230 formed in the floor 214 which is normally closed by doors 232, 234 hingedly connected thereto by conventional means 236.

As seen in FIG. 2, the opening 230 spans across the band catcher and the upper mill wheel 238 of a band saw mill 240, all of conventional construction and being shown in dotted lines. The mill includes supports 242, 244 for journals 246, 248 which receive the opposed ends of the shaft 250 of the upper mill wheel 238 for rotation therein. In the'usual and normal relationship of the upper mill wheel 238 relative to the bandsaw catcher l0, these components confront one another with the block 71 disposed inside the outer periphery of the wheel 238. Thus, when the saw 252 is thrown off the wheel 238 (to the left, as viewed in FIG. 2) it normally trains itself over the blocks 71. This is the position of the bandsaw and its catcher as is illustrated in FIG. 2 of the drawing. To return the bandsaw blade 252 to the upper mill wheel 238 an operator will engage a socket wrench with the head 154 and will turn the same in a given direction causing the collar 164 to move downwardly and in so moving, pull the rod 172 downwardly therewith. This movement causes the levers 98, to pivot in a clockwise direction about the pivot pin 104 whereby the carriage 86 is pivoted from its full line position to its dotted line position of FIG. 3.

The operator also engages the socket wrench with the head to effect a turning movement of the shaft 158 which causes the collar 192 to move downwardly thereon thereby pushing the frames 112, 114 upwardly from the full line position of FIG. 1 to their dotted line positions shown therein. As the frames 1 12, 114 pivot outwardly and upwardly, the apices of the rollers 96 will engage the inner side of the bandsaw 252 at points lower than the lowermost ones ofthe blocks 7 l.

Thereafter, a mechanic standing on the floor 214 will reach into the pit 212 to engage a hook about that edge of the bandsaw 252 remotely disposed with respect to the mill wheel 238 and will pull thereon to cause the band saw to ride on the rollers 96, 96 in the direction of the upper mill wheel 238 (in the direction of the arrows shown in FIG. 2).

It will be understood that as the roller wheels 96, 96' move to their operative positions, the bandsaw blade 252 is elevated above the upper peripheral edge of the mill wheel 238 and is expanded thereabout so that the bandsaw blade 252 may be easily pulled from the aforementioned roller wheels for installation on the mill wheel 23S.

Thereafter, the carriages 86, 86' and their roller wheels 96, 96 are retracted from their dotted line position of FIG. 3 to their full line position shown therein and the bandsaw catcher is again readied to serve its usual function.

Having described and illustrated one embodiment of this invention in detail, it will be understood that the same is offered merely by way of example, and that this invention is to be limited only by the scope of the appended claims. l

I claim: 1. In a bandsaw catcher for a band saw mill having an upper mill wheel, said bandsaw catcher including a downwardly opening arcuate frame having a pair of opposed ends and sides, means on said catcher for supporting said frame with one side thereof disposed in spaced confronting relationship relative to one side of said upper mill wheel, means on said arcuate frame for releasably supporting; the upper looped end of an endless bandsaw blade thereon;

an improvement in said catcher which includes the provision of means for facilitating the transfer of said looped end of said blade from its said support means onto said upper mill wheel and wherein said transfer means comprises:

first means mounted on said arcuate frame normally disposed, in its first operative position, below said blade supporting means; and second means operatively connected with said first means for raising said first means from its first operative position to engage the underside of said looped end of said blade to raise said blade from its said support means in a second operative position of said first means. 2. Apparatus as defined in claim l wherein: said second means includes means operable to shift said looped end of said blade in the direction of said upper mill wheel.

3. Apparatus as defined in claim l wherein:

said second means includes means operable to shift said looped end of said blade in the direction of said upper mill wheel substantially simultaneously with the raising of said blade from its said support means.

4. Apparatus as defined in claim 2 wherein:

said first means includes a plurality of first carriages pivotally supported on said arcuate frame for movement towards said upper mill wheel. to its second operative position and away from said upper mill wheel to its said first operative position; and

a plurality of roller wheels for each carriage means, said roller wheels being arranged in tandem in each of said first carriages and movable in saidsecond operative position of said first carriage transversely to engage the underside of said looped end.

5. Apparatus as defined in claim 4 and:

a second frame pivotally mounted on the opposed ends,

respectively, of said arcuate frame::

second carriage means fixedly connected on said second frame and including a plurality of roller wheels supported for rotation thereon;

said second frame having a first operative position disposed within the arcuate plane of said arcuate frame; and

means operatively connnected with said second frame to move said second frame to a second operative position outside of said arcuate plane of said arcuate frame to cause said roller wheels of said `second carriage means to engage the underside of said blade adjacent said looped end and to thereby expand the opposed sides thereof.

6. Apparatus as defined in claim 5 wherein said bandsaw catcher includes a back frame rigidly connected with said catcher on the other side thereof and wherein:

said means operably connected with said first carriage means includes a shaft joumaled for rotation on said back frame, said shaft threadably receiving a collar thereon for axial movement in response to the turning movement of said shaft;

lever means connected with each of said first carriages;

a rod for each of said carriages;

means pivotally connecting one end of each of said rods with, respectively, one of said lever means; an

means pivotally connecting the other ends of each of said rods on said first collar whereby a turning movement of said first shaft causes said first carriages to pivot relative to said arcuate frame towards and away from their said first and second operative positions, respectively.

7. Apparatus as defined in claim 6 and:

a second shaft joumaled for rotation on said back frame;

a second collar threaded on said second shaft for axial movement relative thereto; and said operable means for said second frames comprising second rods having one of their ends pivotally connected on, respectively, one of said second frames, and their other-respective ends pivotally connected on said second collar whereby the turning of said second shaft causes said second frames to move towards and away from one another. 8. Apparatus as defined in claim 6 and: means interposed in each of said first rods to adjust the effective length thereof. 9. Apparatus as defined in claim 6 and means interposed in said second rods for adjusting their effective length. 

1. In a bandsaw catcher for a band saw mill having an upper mill wheel, said bandsaw catcher including a downwardly opening arcuate frame having a pair of opposed ends and sides, means on said catcher for supporting said frame with one side thereof disposed in spaced confronting relationship relative to one side of said upper mill wheel, means on said arcuate frame for releasably supporting the upper looPed end of an endless bandsaw blade thereon; an improvement in said catcher which includes the provision of means for facilitating the transfer of said looped end of said blade from its said support means onto said upper mill wheel and wherein said transfer means comprises: first means mounted on said arcuate frame normally disposed, in its first operative position, below said blade supporting means; and second means operatively connected with said first means for raising said first means from its first operative position to engage the underside of said looped end of said blade to raise said blade from its said support means in a second operative position of said first means.
 2. Apparatus as defined in claim 1 wherein: said second means includes means operable to shift said looped end of said blade in the direction of said upper mill wheel.
 3. Apparatus as defined in claim 1 wherein: said second means includes means operable to shift said looped end of said blade in the direction of said upper mill wheel substantially simultaneously with the raising of said blade from its said support means.
 4. Apparatus as defined in claim 2 wherein: said first means includes a plurality of first carriages pivotally supported on said arcuate frame for movement towards said upper mill wheel to its second operative position and away from said upper mill wheel to its said first operative position; and a plurality of roller wheels for each carriage means, said roller wheels being arranged in tandem in each of said first carriages and movable in said second operative position of said first carriage transversely to engage the underside of said looped end.
 5. Apparatus as defined in claim 4 and: a second frame pivotally mounted on the opposed ends, respectively, of said arcuate frame:: second carriage means fixedly connected on said second frame and including a plurality of roller wheels supported for rotation thereon; said second frame having a first operative position disposed within the arcuate plane of said arcuate frame; and means operatively connnected with said second frame to move said second frame to a second operative position outside of said arcuate plane of said arcuate frame to cause said roller wheels of said second carriage means to engage the underside of said blade adjacent said looped end and to thereby expand the opposed sides thereof.
 6. Apparatus as defined in claim 5 wherein said bandsaw catcher includes a back frame rigidly connected with said catcher on the other side thereof and wherein: said means operably connected with said first carriage means includes a shaft journaled for rotation on said back frame, said shaft threadably receiving a collar thereon for axial movement in response to the turning movement of said shaft; lever means connected with each of said first carriages; a rod for each of said carriages; means pivotally connecting one end of each of said rods with, respectively, one of said lever means; an means pivotally connecting the other ends of each of said rods on said first collar whereby a turning movement of said first shaft causes said first carriages to pivot relative to said arcuate frame towards and away from their said first and second operative positions, respectively.
 7. Apparatus as defined in claim 6 and: a second shaft journaled for rotation on said back frame; a second collar threaded on said second shaft for axial movement relative thereto; and said operable means for said second frames comprising second rods having one of their ends pivotally connected on, respectively, one of said second frames, and their other respective ends pivotally connected on said second collar whereby the turning of said second shaft causes said second frames to move towards and away from one another.
 8. Apparatus as defined in claim 6 and: means interposed in each of said first rods to adjust the effective length thereof.
 9. Apparatus as defineD in claim 6 and means interposed in said second rods for adjusting their effective length. 